It is already known to connect a speed sensor of a motor vehicle in the form of an rpm sensor directly to an engine control as an evaluation circuit with the sensor being connected via a digital input. The rpm sensor is, for example, mounted on the transmission output end of the motor vehicle. The rpm measured there is an index for the speed of the motor vehicle and is transmitted in the form of a pulse sequence to the digital input of the engine control and is there read in. The received pulse sequence is converted into a vehicle speed in the engine control.